1. Field of the Invention
The present invention relates to a cutter type knife with a blade which is retracted automatically as soon as the plunger, grip or trigger operated to deploy the blade from the handle is released.
2. Description of the Prior Art
Cutters of the above type are known comprising a sliding blade the deployment of which from the handle is commanded by pressing in a plunger on the side of the handle with the thumb, the plunger returning automatically to its initial position corresponding to total retraction of the blade as soon as the pressure exerted on it is removed, by virtue of a return spring disposed within the handle.
This type of instrument features two significant disadvantages. On the one hand, they do not offer a full guarantee of safety when not in use since they are not protected against unintentional partial deployment of the blade from the handle, which can be dangerous and result in injury, when the knife is in a pocket, for example.
On the other hand, they are not very easy to use since doing so requires a constant non-negligible pressure of the thumb on the plunger to hold the blade in the operative position. This is tiring in the long term and causes difficulties to lefthanded persons since the plunger is accessible from only one side of the handle of the knife.
An object of the present invention is to alleviate these disadvantages by proposing a system for automatically retracting the blade which is practical, efficacious and dependable under all circumstances.